1. Field of the Invention
The present invention relates generally to amplifiers, and more specifically to minimizing changes in common mode voltage at inputs of an operational amplifier used in a switched capacitor differential amplifier.
2. Related Art
Differential amplifiers are often employed to amplify (enhance the signal level/strength of) signals. As is well-known, a differential amplifier ideally amplifies the difference between the voltages at its two input terminals, while attenuating/rejecting a voltage common at both the input terminals.
A switched capacitor differential amplifier is a type of a differential amplifier in which charge is switched (transferred) among capacitors connected to various input/output terminals/nodes of an operational amplifier to obtain a desired gain/amplification. Components such as switches are generally employed to obtain the transferring of the charge, as is well-known in the relevant arts.
The operation of an operational amplifier is characterized by a common mode voltage at its input terminals (which may also be viewed as ‘virtual ground’ terminals). As is well-known, common mode voltage generally refers to the voltage level with respect to a reference potential (e.g., ground terminal) that is common (same) at each of the input terminals, and is generally measured as the average of the voltages at the two input terminals.
It is generally desirable to minimize changes in common mode voltage at the input terminals of an operational amplifier. Such minimization can lead to benefits such as reduced distortions in the output signal, etc., as is also well-known in the relevant arts.